def wrote:Pardon me, but what is meant by "basic PI"? Is this something defined by a DE program/mode?

Sorry for the confusion, all I mean by that is just a non-flow based PI... so any infusion of the puck at a certain set pressure for a certain set amount of time. For light roasts I tend to start at 3 bar for 10-12 seconds and adjust my grind so that I'm getting first drips just before ramping up to peak pressure.

Same here, though my go-to profile is a little more Slayerlike...
-Low flow PI in the 1.5ml/s range, metered to this rate through the needle while the pump delivers full pressure
-this goes on with zero pressure on the group pressure gauge while the headspace fills, then slowly builds towards 9 bar (where I have the bypass set on my rotary). This usually takes about 25-30s before the bottom of the basket wets down
-open the needle to 9 bar for 10 seconds or so (if the flow looks a little fast, I close the needle a little to slow it down to where it looks right)
-then the final third of the pull as the puck erodes and the flow wants to speed up, I keep closing the needle to keep the flow rate in check

This is with a Monolith FlatSSP. Ryan and Mike have Maxes and near as I can tell, they can get these kinds of results without having to "Slay" the profile so much as the rest of us mere mortals